Amazon's Sunday delivery service could give it a leg up in the holiday shopping season and boost orders for the money-losing U.S. Postal Service. (Amazon chief executive Jeffrey P. Bezos owns The Washington Post.) (Reuters)

Already, work e-mails and conference calls have become part of Sunday routines, piling on top of sports tournaments, errands and homework. Now, with Amazon.com’s plans to deliver packages on Sundays, one more barrier falls, inching that day even closer to becoming just another part of the consumer week.

The tradition of a seventh day set aside for family and rest has been crumbling for years as states relaxed laws prohibiting gambling, shopping and even hunting on Sundays. The popularity of smartphones and the creation of an always-online culture has spurred greater demand — and ability — to have it all, right now, anytime.

“We are moving toward a society where e-mail and social media have caused the week and weekend to blur,” said Jonathan Gruber, a professor of economics and labor at MIT.

“Blue laws” that ban Sunday activities — dating to the 1600s — have been gradually repealed in many states, but some remain. In Maryland, car sales on Sundays are widely banned, though they are allowed in Montgomery, Prince George’s and Howard counties.

Sunday hunting is banned in many states. In Virginia, the rules are more specific: Hunting with firearms or other weapons is banned on Sundays, though raccoons may be hunted until 2 a.m.

As cities and states look for more revenue, they have loosened laws banning liquor sales on Sundays. The D.C. Council approved a plan to allow them late last year, and liquor stores in Montgomery County were allowed to sell on Sundays starting in 2010. A new law that took effect last year in Virginia allowed state-run stores in small communities to start selling alcohol on Sundays

Amazon’s national plan to partner with the U.S. Postal Service could open the door to a wave of Sunday deliveries by other companies. The money-losing Postal Service, which recently was trying to persuade Congress to halt Saturday mail, said it will expand Sunday staffing and hopes to sign up more clients. The agency declined to disclose specifics or to reveal how much new revenue it expects.

There were no complaints about prolonging the workweek from a union representing letter carriers. “We’re excited about the potential of the rapidly growing e-commerce market and what it means for the Postal Service,” said Fredric Rolando, president of the National Association of Letter Carriers. Expanding Sunday service “would benefit the economy, consumers, businesses and the nation as a whole,” he said.

Amazon said its plan originated from consumer demands to get their online orders faster.

Competitors such as Wal-Mart, eBay and Google are racing to satisfy consumers virtually around the clock, aiming to deliver products just hours after someone places an online order.

“Amazon’s announcement is another incremental development in the erosion of that restful space — Sunday — and another example of an erosion on the limits of market activity,” said Jordan J. Ballor, a research fellow at the Acton Institute for the Study of Religion and Liberty, an economic think tank.

The changes of shopping patterns began well before online commerce took off. Wal-Mart, Kmart and other major retailers were criticized when they started opening their stores on Sundays years ago. Since then, they have expanded shopping hours to 24 hours a day and holidays. They have faced renewed backlash over plans to open on Thanksgiving Day.

Last year, an employee of Target wrote a letter to company chief executive Gregg W. Steinhafel, asking him to close the chain of stores on Thanksgiving. The letter was posted as a petition on Change.org and got more than 300,000 signatures of support.

The company stood by its decision to open on Thanksgiving evening, saying it was responding to the interests of shoppers and of employees who asked to work the overtime shifts.

In an age of constant commerce, consumers have struggled to reconcile their urge to spend with older traditions of quiet Sundays. Last month, some residents of Bergen County, N.J., tried to repeal a county ban on the sale of furniture, clothing and electronics on Sundays. They had argued that opening retail stores seven days a week would boost the local economy. But they failed to get enough signatures of support.

A few companies have resisted the seven-day trend. Chick-fil-A’s 1,700 fast-food restaurants and Hobby Lobby’s 560 craft stores are closed on Sundays.

Chick-fil-A’s founder believes that “all franchised Chick-fil-A operators and their restaurant employees should have an opportunity to rest, spend time with family and friends, and worship if they choose to do so,” according to a statement on the company’s Web site.

But such cases are rare. The combination of weaker labor unions, fewer blue laws and greater consumer demand has made it easier for companies to get away with e-mails during off-hours and stores open at all hours, said Nelson Lichtenstein, director of the Center for the Study of Work, Labor and Democracy at the University of California at Santa Barbara.

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